With internal combustion engines, transmissions, and other machinery requiring fluids for lubrication and cooling, it is known to use a fluid measuring device for indicating the fluid level in a selected fluid holding compartment. Typically, the fluid measuring device is a dipstick for checking the level of fluid such as engine or transmission oil, or hydraulic fluid within one of the many fluid holding compartments in the engine, transmission, or other machine. The dipstick is normally an elongated indicator that is slidably located within a conduit or pipe attached to the engine, transmission, gear box, reservoir or machine in which a fluid level indication is desired. When the dipstick is fully inserted into the conduit, one end is immersed into the fluid. When an actual reading of the fluid level is desired, the other end of the dipstick is pulled from the conduit thereby removing the entire dipstick from the conduit to allow the user to read the fluid level from the one end. The dipstick is then reinserted into the fluid compartment once the fluid level has been checked.
Traditional fluid level indicator systems typically consist of a two piece system with a holding tube and a dipstick. Examples of conventional dipstick systems are disclosed in U.S. Pat. Nos. 3,371,418; 5,485,681 and 5,829,153; the disclosure of each of which is hereby incorporated by reference. The holding tubes are generally fabricated from metal tubing and require various forming operations including bending, flaring, and machining, followed by the attachment of a dipstick receptacle. In addition, the dipstick is fabricated from multiple components including a handle, washer, cap, rubber stopper, shaft assembly, and a marked spring steel shaft mechanically joined to a spring steel blade. The actual assembly of these various components involves multiple assembly operations requiring costly, time-consuming, and labor intensive manufacturing steps. Therefore, a simpler design requiring fewer parts and connections as well as less forming is desirable.
In addition, today's engines, transmissions, and machinery designs are smaller, more compact, and of less weight than traditional engines, transmissions, and machinery. Therefore, fluid level indicator systems must be smaller, more compact, and lighter weight. Moreover, the fluid access routes or paths through which the fluid level indicator system accesses the fluid storage compartments are becoming more complex (more twists and turns as well as longer runs), smaller, and more compact.
There is a need in this art for smaller and lighter weight fluid level indicator systems with improved flexibility. There is also a need for a fluid level indicator system allowing access to the fluid compartment while assuring a secure, sealed closure of the access when fluid level determinations are not being made and/or additional fluid is not being added. This sealed closure would prevent unnecessary loss of the fluids during operation as well as supply level pressurization. Moreover, a positive indication that the dipstick is securely in place is desirable.